1. Field of the Invention
This application relates to motion estimation in display devices. In particular, this application relates to systems and methods for determining motion vectors for blocks of frame data.
2. Description of the Related Technology
In recent years, advancements in digital video processing have allowed video display manufacturers to produce systems which provide a more realistic viewing experience by enhancing raw digital video. Motion estimation algorithms are commonly used in providing enhanced video. For example, motion estimation algorithms are often utilized when performing de-interlacing of video, video format conversion, and frame rate conversion. Among the different types of motion estimation algorithms, block matching algorithms are often chosen for their superior trade-off between complexity (which is relatively low) and accuracy (which tends to be high). Block matching algorithms generally compare a given arbitrary block in one frame of video to one or more blocks from another frame of video in order to find a suitable matching block.
Recursive search techniques form one category of block matching algorithms. Recursive motion estimation typically involves evaluating a limited set of candidate motion vectors to determine the best motion vector for a given block of pixels in a video frame. In implementing a recursive search strategy, a specific recursion rule is typically selected that determines the candidate motion vectors to be evaluated. Each recursion rule has certain characteristics. As a result, the use of a specific recursion rule may often result in certain performance advantages and disadvantages. For example, some recursive rules may generally perform well and be computationally inexpensive but they may not be well-suited for cases of sudden or rapid change in motion of objects. Other recursion rules may perform adequately in cases of sudden or rapid change in motion of objects, but may be sensitive to problems such as noise, low dynamic range, and multiple matches. Accordingly, it would be useful to provide a motion estimation technique designed to alleviate shortcomings associated with the use of a single recursion rule.